Field of Invention
The present invention relates to a method of manufacture of fiberboard, and more particularly to a method of manufacture of medium and high density fiberboard which is moisture resistant, mildew resistant and has low formaldehyde emission.
Description of Related Arts
In the process of manufacture of wood-based panels, a large quantity of adhesive is used and the adhesive will introduce ‘unstable’ factors. When the pH is low or when the humidity level is high, the chains of the adhesive will break down and decompose to emit free formaldehyde. Under the action of electrolytes in the heating and pressing process, free formaldehyde will also be emitted. At present, the manufacture of high density fiberboard mainly includes the steps of: preparing materials (by chipping or purchasing wood chips; selecting and cleaning of wood chips, pre-steaming, steaming, milling and heating, adjusting and applying glue, drying, mat forming, pre-pressing, hot pressing, cutting, cooling, sanding, sawing and quality inspection. The medium and high density fiberboards manufactured by the above conventional process, which includes conventional technology and process of materials preparation, steaming, hot-pressing and glue adjustment and preparation, can only meet the standard of ordinary fiberboard. In recent years, a clear market segmentation phenomenon gradually occurred with the rapid development of fiberboard industry. In particular, users have an increasingly higher product quality standard requirements and environmental awareness. The market has an urgent need of a new type of high quality and environmental friendly fiberboard materials which is convenience for color match, water resistant, mildew resistant and has low formaldehyde emission to suit the need of market development in fashion and design industries. In response to the above market requirements, many manufacturers in this industry added paraffin or waterproofing agent to solve the moisture problem. Though this method may work well to prevent water moisture, this method has the problem of great variation of raw material quality, and does not provide the function of mildew resistant and bacteria inhibition. In view of the problem of formaldehyde emission, the formulation of the adhesive is adjusted. Urea-formaldehyde based resin is replaced by other resins of much high manufacturing cost. The use of methylene diphenyl isocyanate (MDI) resins or soybean bio-glue provides satisfactory effect but the production cost is very high and the price is very expensive, which is not affordable by general users.